The shining green-and-white ship is the third rendition of the Rainbow Warrior, and the first built entirely to Greenpeace specifications.

A-frame masts allow crew to move the mast stays to accommodate a helicopter landing, and make space to store the aircraft below deck.

That’s invaluable when the ship is investigating illegal fishing or operating off the coast of Africa in areas prone to piracy, said Greenpeace spokeswoman Myriam Fallon.

Rigid-hulled inflatable boats can be deployed in less than a minute, she said, allowing crews to take swift actions, such as hanging banners on targets of their protest, or pulling suspected illegal fishing gear.

It’s designed to carry specialized scientific equipment and has a built-in satellite uplink, making it “a floating communication’s hub,” according to the Greenpeace website.

“She’s the ship of dreams for me,” said Penny Gardner, the ship’s bosun, or equipment officer.

The latest ship was also built to be, well, greener than ever.

The ship relies on wind power whenever possible, but also features an efficient diesel-electric engine, exhaust filters and biological treatment of wastewater.

“It’s nice to have a vessel that lets us put our money where our mouth is, that’s designed around sustainability and renewable energy, and lets us take our campaigns into the next century,” said Casson Trenor, a Greenpeace oceans campaigner.

While the first two Rainbow Warriors were fishing trawlers outfitted with sailing masts, the new ship was fashioned after super-yachts by a Dutch ship maker. At 190 feet long and 180 feet tall from water to the mast top, it’s one of the larger sailing vessels in operation, Fallon said. It went into service in late 2011.

Its construction cost of $33 million was crowd-sourced through an online effort that allowed donors to contribute a single dollar to fund a bolt, or larger amounts to sponsor a portion of rail or decking.

While crew members are focused on the fate of 30 Greenpeace activists imprisoned in Russia for actions there, they have ventured into risky territory of their own.

Early last year, the ship’s first major action on its maiden voyage, said captain Joel Stewart, was “blocking a pig iron ship in Brazil that was using slave labor and timber from protected, indigenous land.”

The ship will also campaign against Arctic oil drilling and offshore coal extraction, officials said.

The Rainbow Warrior’s stop in San Diego aimed to protest tuna giants Bumblebee and Chicken of the Sea, for what activists said are unsustainable fishing practices.

But Gavin Gibbons, a spokesman for the National Fisheries Institute, a fishing trade association, said the companies have already adopted sustainable practices, and called the Rainbow Warrior visit a fundraising operation.

“This is a group that has refused to join science-based sustainability efforts and has chosen instead to panhandle,” Gibbons said.

Stewart said, however, one goal of the ship’s visit was to foster such debates.

“One of our principles is to invite everybody down — not only our supporters, but also people who don’t think that they like us — to have a dialogue,” he said.

The ship is open for free tours Sunday from 10 a.m. to 5 p.m. at the Embarcadero.